Bandgap voltage reference circuits combine a signal from a Proportional to Absolute Temperature (PTAT) source with a signal from a Complementary to Absolute Temperature (CTAT) source to provide a temperature independent and stabilized voltage reference signal, that can then be used in all manner of circuitry, including RF circuitry such as modulators, demodulators, and phase-locked loops, as well as in digital circuitry such as analog-to digital to converters (ADCs). In order to limit the noise bandwidth of the reference signal, often large (μF size) capacitors are used at the output of the reference, which means that the bandgap voltage reference circuit is constantly powered to provide a constant reference source, as it would not be energy efficient to charge and discharge such large capacitors to duty cycle the reference. Hence even though the actual reference signal may not be needed by the system that uses it all the time, because of the presence of the large noise filtering capacitor such references are usually continually operated whilst the system is powered up, hence wasting power.